Cytokine supplemented maturation medium improved development to term following somatic cell nuclear transfer (SCNT) in cattle.

Abstract

Context: In vitro maturation is an important process in the production of embryos. It has been shown that three cytokines, fibroblast growth factor 2, leukemia inhibitory factor and insulin-like growth factor 1 (FLI), increased efficiency of in vitro maturation, somatic cell nuclear transfer (SCNT) blastocyst production, and in vivo development of genetically engineered piglets.

Aims: Assess effects of FLI on oocyte maturation, quality of oocytes, and embryo development in bovine in vitro fertilisation (IVF) and SCNT.

Key results: Cytokine supplementation resulted in significant increases in maturation rates and decreased levels of reactive oxygen species. Oocytes matured in FLI had increased blastocyst rates when used in IVF (35.6%vs 27.3%, P <0.05) and SCNT (40.6%vs 25.7%, P <0.05). SCNT blastocysts contained significantly more inner cell mass and trophectodermal cells when compared to the control group. Importantly, SCNT embryos derived from oocytes matured in FLI medium resulted in a four-fold increase in full-term development compared to control medium (23.3%vs 5.3%, P <0.05). Relative mRNA expression analysis of 37 genes associated with embryonic and fetal development revealed one gene had differential transcript abundance in metaphase II oocytes, nine genes at the 8-cell stage, 10 genes at the blastocyst stage in IVF embryos and four genes at the blastocyst stage in SCNT embryos.

Conclusions: Cytokine supplementation increased efficiency of in vitro production of IVF and SCNT embryos and in vivo development of SCNT embryos to term.

Implications: Cytokine supplementation is beneficial to embryo culture systems, which may shed light on requirements of early embryo development.